Frictional drive device and inverted pendulum type vehicle using the same

Abstract

A frictional drive device comprises a pair of drive disks ( 48 ) each rotatably supported by a frame ( 2, 42 ) around a central axial line (A) in a mutually opposing relationship, and a pair of actuators ( 64 ) supported by the frame for individually rotatively actuating the drive disks and coaxially disposed with respect to the corresponding drive disks, a plurality of drive rollers ( 56 ) arranged along an outer periphery of each drive disk and each having a rotational center line so as to be rotatable along a plane which is neither parallel nor perpendicular to the central axial line, and an annular main wheel ( 85 ) disposed approximately coaxially with respect to the central axial line and engaged by the drive rollers of the drive disks, the main wheel comprising an annular member ( 86 ) and a plurality of driven rollers ( 92 ) supported along the annular member so as to be rotatable around a tangential line of the annular member. A speed reduction unit ( 72, 100 ) may be interposed between each actuator and the corresponding drive disk all in a coaxial relationship.

1. A frictional drive device, comprising
 a frame; 
 a pair of drive disks each rotatably supported by the frame around a central axial line in a mutually opposing relationship; 
 a pair of actuators supported by the frame for individually rotatively actuating the drive disks; 
 a plurality of drive rollers arranged along an outer periphery of each drive disk and each having a rotational center line so as to be rotatable along a prescribed plane of rotation; and 
 an annular main wheel disposed approximately coaxially with respect to the central axial line and engaged by the drive rollers of the drive disks, the main wheel comprising an annular member and a plurality of driven rollers supported along the annular member so as to be rotatable around a tangential line of the annular member; 
 wherein each actuator comprises a rotary actuator coaxially disposed with respect to the corresponding drive disk. 
 
     
     
       2. The frictional drive device according to  claim 1 , wherein the two drive disks are connected to each other by a coupling mechanism that couples the two drive disks in a mutually freely rotatable manner while preventing at least radial relatively movement between the two drive disks. 
     
     
       3. The frictional drive device according to  claim 1 , wherein the two drive disks are connected to each other by a coupling mechanism that couples the two drive disks in a mutually freely rotatable manner while preventing at least axial relatively movement between the two drive disks. 
     
     
       4. The inverted pendulum type vehicle according to  claim 1 , wherein the prescribed plane of rotation is neither parallel nor perpendicular to the central axial line. 
     
     
       5. The frictional drive device according to  claim 1 , wherein a plurality of slots are formed along a peripheral part of each drive disk, each slot extending along the prescribed plane of rotation, and each drive roller is rotatably supported by the drive disk via a roller shaft passed perpendicularly across the corresponding slot. 
     
     
       6. The frictional drive device according to  claim 5 , wherein a low frictional coating is formed on at least one of mutually sliding surfaces of each drive roller and an opposing wall surface of the corresponding slot. 
     
     
       7. An inverted pendulum type vehicle using the frictional drive device as defined in  claim 1  as a drive unit, wherein the main wheel is used as a road contact wheel. 
     
     
       8. The inverted pendulum type vehicle according to  claim 7 , wherein each actuator comprises an electric motor, and the vehicle is provided with a vertically elongated vehicle frame, a battery for powering the electric motor being mounted on an upper part of the vehicle frame, and the drive unit being mounted on a lower part of the vehicle frame. 
     
     
       9. The frictional drive device according to  claim 1 , wherein each actuator at least partly overlaps with the drive rollers of the corresponding drive disk along the central axial line thereof. 
     
     
       10. The frictional drive device according to  claim 9 , further comprising a speed reduction unit for transmitting a rotational output of each actuator to the corresponding drive disk at a reduced speed ratio, the actuator, speed reduction unit and drive disk being arranged in a coaxial relationship. 
     
     
       11. The frictional drive device according to  claim 10 , wherein the speed reduction unit comprises a wave gear device. 
     
     
       12. The frictional drive device according to  claim 10 , wherein the speed reduction unit comprises a planetary gear device.